Atmospheric acid deposition is of environmental concern worldwide, and the determination of impacts in remote areas can be problematic. Rainwater in central Pennsylvania, USA, has a mean pH of approximately 4.4. Bedrock varies dramatically in its ability to neutralize acidity. A GIS database simplified reconnaissance of non-carbonate bedrock streams in the Valley and Ridge Province and identified potentially chronically impacted headwater streams, which were sampled for chemistry and brook trout. Stream sites (n=26) that originate in and flow through the Tuscarora had a median pH of 5.0 that was significantly different from other formations. Shawangunk streams (n=6) and non-Tuscarora streams (n=20) had a median pH of 6.0 and 6.3, respectively. Mean alkalinity for non-Tuscarora streams (2.6 mg/L CaCO(3)) was higher than the mean for Tuscarora streams (0.5 mg/L). Lower pH and alkalinity suggest that the buffering capability of the Tuscarora is inferior to that of adjacent sandstones. Dissolved aluminum concentrations were much higher for Tuscarora streams (0.2 mg/L; approximately the lethal limit for brook trout) than for non-Tuscarora streams (0.03 mg/L) or Shawangunk streams (0.02 mg/L). Hook-and-line methods determined the presence/absence of brook trout in 47 stream reaches with suitable habitat. Brook trout were observed in 21 of 22 non-Tuscarora streams, all 6 Shawangunk streams, and only 9 of 28 Tuscarora stream sites. Carefully-designed hook-and-line sampling can determine the presence or absence of brook trout and help confirm biological impacts of acid deposition. 15% of 334 km of Tuscarora stream lengths are listed as "impaired" due to atmospheric deposition by the Pennsylvania Department of Environmental Protection. 65% of the 101 km of Tuscarora stream lengths examined in this study were impaired."

so streams in Tuscarora bedrock may be hit harder by acid rain... so where's the Tuscarora bedrock? see the map here, for ex parts of NW Union county:

These problems sadden me. I knew it was a matter of time before invasive species found there way to central PA, but I kept hoping it wouldn't happen for a long time. The acid rain issue is one thing I haven't thought about for a long time. I know its an issue, and has been worse than it is now, but I don't pay much attention to it. It has always seemed that acid mine drainage was the real problem acid related problem for PA streams.

well the article above suggests that areas with low-alkalinity Tuscarora bedrock will have worse acidity in streams, so they may be less likely to have trout. I looked at some areas with that bedrock ... tuscarora bedrock areas are in lime green below (for ex, SE of Williamsport and just S of Middleburg).

Most PA ridges have different bedrock, so maybe more brookies... For ex, the article above says some non-Tuscarora streams had median pH of 6.3, and streams w/no acid rain effect might be 6.5 pH... still, I have fished in some of these tuscarora bedrock areas, will try to consider this issue in this part of the state.

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Posted on: 2014/3/25 7:39

Edited by k-bob on 2014/3/25 7:54:48Edited by k-bob on 2014/3/25 7:55:45Edited by k-bob on 2014/3/25 7:56:34Edited by k-bob on 2014/3/25 7:58:35

Besides Swift Run, another stream in the region is the headwaters of Middle Creek. west of Pleasant Grove.

The stream originates and flows about 4 miles through Bald Eagle State forest. The surroundings and watershed are forested. But PFBC surveys and surveys by the people at Bucknell found no trout.

It's a similar situation, a stream originating and flowing through Tuscarora geology, weakly buffered, so the ph and alkalinity are very low.

After studying these streams, Dr. Carl Kirby from Bucknell initiated a liming project in the headwaters of Buffalo Creek, and reports are that there are a few brookies there now.

There was an article about this in Trout magazine and in PA Trout newsletter. The return of the brookies there is good news but the article said the ponds may only work for 20 years, so it doesn't sound like a long term solution.

>>The acid rain issue is one thing I haven't thought about for a long time. I know its an issue, and has been worse than it is now, but I don't pay much attention to it. It has always seemed that acid mine drainage was the real problem acid related problem for PA streams. >>

It isn't always an either/or between the two causes of acidification and the problems they pose for Pennsylvania streams. Quite a few of the AMD discharges, especially around the edges of the historic bituminous regions of the state, are more aptly described as seeps. They are low volume and may only impact the receiving stream during high flow periods. So, they can be present in streams that still fish fairly well and appear relatively healthy because their effects are buffered out in an otherwise AMD-free watershed. But chronic acid deposition from rainfall can deplete the thin lifeline of buffering capacity in these streams and push them over the edge into full acidification.

So, in some PA streams, the effects of the two sources are additive. The streams can handle (and at least remain somewhat viable) either limited AMD seeps or low Ph rainfall, but not both. I think if you look along the edges of the old coal region, you'll see a number of streams where this is or has been the case. One that comes to mind (and where the remaining AMD has been eliminated and the stream has rebounded some) is the Coon Creek watershed in the lower Tionesta drainage. But I would imagine you could find quite a few more if you drew an arcing line from Tionesta/Leeper east to say, Lock Haven and took a look at the streams that cross this line flowing north.

Acid rain is a problem and will continue to be a problem. After all, all of those native brook trout lakes spread throughout the Adirondacks have been hurt very badly by acid rain and invasive species. Pike, bass, and perch are all major concerns in overshadowing the brook trout there. Is it bad? Yes and no. If the water is too acidic for brook trout anyway there might as well be some fish in there. I love them all. I do wish that things would stay "undamaged" and "unchanged" but we all like cars, electricity, and what not and it is going to be nearly impossible to balance it all with the ever growing human population.